Rolling mill



July 3, 1934. w. ROHN 1,964,893

ROLLING MILL Filed April 30. 1931 v 4 Sheets-Sheet 1 0 a Fzg7 (0.40FLOR/4.)

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July 3, 1934. ROHN 1,964,893

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ROLLING MILL Filed April 30, 1931 4 Sheets-Sheet 3 W. ROHN ROLLING MILLJuly 3, 1934.

Filed April 30. 1931 4 Sheets-Sheet 4 J72 ventm:

6 fimj Patented July 3, 1934 UNITED STATES PATENT OFFICE ApplicationApril 30, 1931, Serial No. 534,085 In Germany January 28, 1929 3 Claims.

This invention relates to improvements in rolling mills.

For the purpose of rolling strips there have been introduced to anincreasing extent rolling mills having six rolls with driven operatingrolls, the operating rolls being provided with bearing pivots andcoupling pivots. It would be possible to increase the economy in suchrolling mills if it were possible to reduce the cost of the operating itrolls which are subjected to wear and to shorten the time necessary forchanging these rolls. These results are obtained by the inventionhereinafter described.

The present invention comprises a rolling mill it with two-pivotlessoperating rolls consisting of simple plain solid or hollow cylinders andtwo pairs of thicker rolls supporting the said operating rolls. The useof pivotless operating rolls has been proposed in connection with fourroll rolling 2h mills (Figure 1), wherein .the axes of all the fourrolls are located in the same or substantially the same plane. In Figure1 a, a indicate the operating rolls, b and c the supporting rolls. Inconnection with four roll rolling mills the use of pivotless operatingrolls has led to an absolute failure. In this connection it is necessaryto arrange in front of and behind the central operating rolls bearingbushlike supports in order to prevent the operating rolls from moving inthe direction of rolling or in the opposite direction thereto. Be-

tween these bearing bush-like supports and the operating rollsunallowable high friction is set up which under circumstances may evencause the operating rolls to stop, whereby the supporting rolls slip onthe operating roll and thus damage this. This friction is considerablyincreased if the strip when entering or leaving the rolls is tightlytensioned which, as is well known, is of the greatest importance forobtaining a smooth and to straight strip. These tensions also render itimpossible to prevent the operating rolls from moving in the rollingdirection or oppositely thereto by the provision of small supportingrolls in front of and behind the operating rolls, as these supportingrolls can only be made very small and are, therefore, not capable ofwithstanding the high strains.

Applicant has found that these difiiculties are immediately eliminatedif pivotless operating rolls are used in combination with supportingpairs of rolls as in this case the operating rolls are simultaneouslyprevented automatically from moving in the rolling direction or oppositethereto and this without any disadvantages, so that even the strongestpulling efforts applied to the entering or outgoing strip do not produceany disturbances.

By reason of the pressure components and the bearing of each operatingroll against two supporting rolls, the driving action exerted by thesupporting rolls on the operating rolls is so great that the liabilityof a stopping of the operating rolls is practically entirely obviated.

The invention will now be described with reference to the accompanyingdrawings wherein Figure 1 shows diagrammatically a known four highrolling mill which is being referred to for the purpose of comparisonwith the rolling mill according to the present invention.

Figure 2 is a diagrammatic end view of a six high rolling mill accordingto the invention.

Figure 3 is a section of a rolling mill taken along the line 3333 ofFigure 2.

Figure 4 is a side view partially in section of a similar rolling mill.

Figure 4a is a detail of Figure 4 on an enlarged scale.

Figure 5 shows by end view a detail of the upper part of Figure 4.

Figure 6 shows a six roll rolling mill provided with a special kind ofrolls.

Figure 7 shows a special design of rolls of a six high rolling mill asillustrated in Figure 6.

Figures 8 and 9 show two forms of supporting rolls and Figures 10 and 11illustrate two forms of operating rolls.

The arrangement of a six roll rolling mill is illustrateddiagrammatically in Figure 2 wherein a, a indicate the operating rolls,1), b the upper supporting rolls and c, c the lower supporting rolls.

As will be seen from this figure the use of pivotless operating rolls,as already suggested in four roll rolling mills, but inoperativetherein, is capable of being used with an eflicient result by theaddition of pairs of supporting rolls.

These plain pivotless rolls, however, only cost one-fourth to one-sixthof the price of rolls of the same size provided with pivots. Thesubsequent regrinding of worn rolls is also considerably cheapened as itis unnecessary to regrind pivots which have become rough. In some casesthe regrinding may even be carried out by the centerless method.

It is unnecessary to provide any further bearing for the lower operatingroll. During idle running the upper operating roll should be heldinloose contact with the upper supporting rolls when these are raised.This can be effected in various ways. For example, in the end surfacesof the roll a there are provided recesses e (Figure 4) in which aremounted center point bearings or auxiliary ball bearings f. The shaft nof the bearing may be fixed to the block it by means of bolts 2'. Toenable the withdrawing of the upper operating roll through the block k,a part of the frame is cut out and the shaft n is screwed to the part 0.This part 0 is fixed to the block is by screws p and 9'. Afterunscrewing the screw p the part 0 may be swung outside and then aroundthe screw p into the position indicated in Fig. 5 by dotted lineswhereupon roll a may be withdrawn. In order to prevent lateral movementof the operating rolls a, a the ball bearings ,f may be constructed soas to form at the same time axial thrust bearings (Figure 4) thepivotless operating rolls having in their axial direction a certainclearance between these thrust bearings so that the end surfaces of therecesses e of the operating rolls only come into contact with the thrustbearings when the operating roll tends to move laterally.

Another arrangement for holding the upper operating roll in contact withthe supporting rolls consists, for example, in mounting in the upperframework at both ends of the operating roll a at the right and lefthand thereof, small trailing rolls (1 and (1 (Figure 3) which may befixed upon rods it connected by springs 12, c (Figure 2) to joints m andm and being capable of being bent outwardly for the purpose of enablingthe operating roll to be changed.

The driving mechanism consists of a motor E driving, for instance, thegear 2 which meshes with a pair of gear 1 and the gearing roll 3,meshing with a pair of gear 4. The pairs of gearing rolls 1 and 4 arecoupled with the supporting rolls b, b and c, c by coupling devices qand q. In addition to the low cost of these simple operating rolls, arolling mill according to the invention also has a further and veryimportant advantage, namely that the operating rolls (whichsubstantially solely are liable to wear, whereas the supporting rollsare hardly exposed to any wear) can be exchanged in less than fiveminutes.

Should it be desirable in exceptional cases to operate, instead ofemploying driven supporting rolls as described, in the manner hithertousual with six roll rolling mills, that means with driven operatingrolls, the coupling devices q and q between the supporting rolls b, band c, c and the corresponding pairs of gearing rolls 1 and 4 foreffecting the drive of the supporting rolls are simply removed. Thepivotless plain cylindrical operating roll may then be replaced byoperating rolls provided with pivots. These can be driven directly bythe provision of coupling devices between the gearing rolls 2 and 3 andthe operating rolls. By this construction allowing to change pivotlessoperating rolls and operating rolls provided with pivots it becomespossible to carry out the greatest part of the rolling work, forinstance, 1% of the total work in the new manner with pivotlessoperating rolls while only of the total work may be carried out ifnecessary, with operating rolls provided with pivots.

Another modification of the subject of the invention is obtained byreplacing the solid pivotless operating rolls as shown in Figures 3-5 byhollow cylinders, serving as pivotless operating rolls which are simplyloosely fitted on driving shafts as shown in Figures 6 and 7. There isno need to machine the internal bores accurately and the rolls shall notfit closely on the driving shafts as the guiding and supporting thereofis solely effected by the supporting rolls.

In Figure..6 the motor E drives the gearing 2 which meshes with thegearing 3. The shafts of the gearings 2 and 3 are coupled by thecoupling devices Q and Q, driving the shafts r and r connected with thehollow rolls. These driving shafts r and r and the hollow operatingrolls A and A may be coupled together by any suitable coupling device,for instance bolts 3 fixed to the shafts r and 1-. Corresponding tothese bolts the ends of the rolls A and A are grooved at t. The moremovable the hollow rolls remain relatively to the driving shafts theless the driving shocks and spindle vibrations will be capable of actingon the material which is being rolled so that a simplified driving trainis sufficient. It has been previously proposed to mount rolls withsquare holes fitting exactly on square or non-circular shafts. Thisarrangement does not, however, lead to any reduction in expense as theproduction or formation of non-circular holes causes considerableexpenses whereas hollow rolls with non-machined bores cost onlyone-third to one-fifth of corresponding rolls provided with pivots. Theproposal referred to above was in respect of two roll rolling mills sothat a complicated and expensive mounting of the pivotless rolls wouldbe necessary, as well as an exact coincidence of the axis of the surfaceof the roll with the axis of the hole. The use of hollow rolls fittingonly loosely on the shafts has the further advantage that the rolls canbe exchanged in a fraction of the time required for changing pivotedrolls. In the selected constructional example it is only necessary torelease the nuts w (Fig. 6) whereupon the hollow rolls which are looselymounted on the driving shafts can be stripped off by two grasps. Thesecuring of the rolls on the driving shafts can be effected in variousways and it is only necessary to provide for rapid detachability.

It may also be mentioned that the hollow rolls are only slightly liableto defect when hardening and acquire a better hardness. A simplificationof the constructional arrangement of the rolling mill itself is alsoobtained by using hollow rolls, as in mainy cases coupling spindles andcoupling sleeves may be omitted as the rolls loosely mounted on thedriving shafts already possess sufficient resiliency which mustotherwise be obtained by the interposition of coupling sleeves.

For smaller or lighter rolling mills the driving shafts may be madesomewhat longer and thinner so that they can bend directly. Such adevice is illustrated in Figure '7 wherein A again in-- dicates a hollowoperating roll, s a coupling or lost-motion device consisting of a slotin the roll A and a pin in the shaft R and R a comparatively long andthin driving shaft.

An essential improvement in the rolling industry is obtained when usingpivotless operating rolls in six roll rolling mills as only acomparatively short time is required for exchanging the rolls. Thiscircumstance is of particular importance when it is desired to roll inthe rolling mill a material which has very different degrees ofhardness, that is to say that the material to be rolled alternatelyconsists of different materials or by reason of previous annealing hasacquired different degrees of hardness. In such cases it is desirablefor each material to be rolled or for each separate condition of thematerial to be rolled to use rolls having an arched surface (Fig. 8),that is to say having a longitudinal curvature deviating from a truecylinder, which corresponds with the actual hardness of the materialunder consideration. Hitherto an exchange of rolls between two sucessiveoperations was too tedious and the rolls provided with pivots were tooexpensive to permit of a frequent exchange of the rolls. When usingpivotless rolls consisting of solid or hollow cylinders it is di rectlypossible to effect two directly succeeding rolling operations with rollsof different longitudinal curvature. It is well known that incorrect orunsuitable longitudinal curvature is the cause of the greatest portionof the scrap and waste occurring during cold rolling. In spite of thisit was not possible to utilize this knowledge hitherto as the exchangeof rolls lasted too long and the high cost of rolls provided with pivotsprevented the keeping in stock of a large number of rolls of differentlongitudinal curvature. The present invention enables the rolls to beexchanged within a few seconds and to use the roll having the desiredlongitudinal curvature when passing from the first to the second andthird operations after annealing or when passing from one kind ofmaterial to another with a different hardness or from one thickness ofmaterial to another thickness.

In the above circumstance lies a further commercial improvement of greatimportance, which it has only been possible to render useful by thepresent invention.

Finally, it is also possible in the case of six roll rolling machines,wherein always the same work is to be carried out, to give thesupporting rolls the desired longitudinal curvature (Figs. 8 and 9)whilst the pivotless operating rolls are made without longitudinalcurvature as exact cylinders.

unmachined inner surface and being put with some clearance on drivingshafts entirely penetrating the hollow cylinders and bearing removableabutments at their ends, and loose couplings between the shafts and thehollow rolls to permit of a certain flexibility between the drivingmeans and the hollow roll.

2. A rolling mill comprising a housing with two pairs of supportingrolls, these rolls supporting two simple pivotless working rolls ofsmaller diameter than the supporting rolls, the working rolls consistingof hollow cylinders with unmachined inner surface, and furthercomprising driving shafts entirely penetrating the hollow cylinders andbearing removable abutments at their ends on which the saidworking-rolls are put with some clearance, and a lost-motion device forcoupling the said hollow working-rolls to said driving shafts.

3. A rolling mill comprising a housing supporting two pairs of "olls,these rolls supporting two simple pivotless working-rolls of smallerdiameter than the supporting rolls, the workingrolls consisting ofhollow cylinders with unmachined inner surface, driving shafts entirelypenetrating the hollow cylinders and bearing removable abutments attheir ends on which the said operating rolls are mounted loosely, thedriving shafts being so long and thin, that they are capable ofsubstantial bending.

WILHELM ROHN.

